<h4>Tool</h4><table border="0"><tr><td valign="top"><b>Name</b></td><td valign="top">Upslope Area</td></tr><tr><td valign="top"><b>ID</b></td><td valign="top">4</td></tr><tr><td valign="top"><b>Author</b></td><td valign="top">(c) 2001 by O.Conrad</td></tr><tr><td valign="top"><b>Specification</b></td><td valign="top">grid</td></tr></table><hr><h4>Description</h4>This tool allows you to specify target cells, for which the upslope contributing area shall be identified. The result will give for each cell the percentage of its flow that reaches the target cell(s).

References:

Deterministic 8
- O'Callaghan, J.F. / Mark, D.M. (1984):
    'The extraction of drainage networks from digital elevation data',
    Computer Vision, Graphics and Image Processing, 28:323-344

Deterministic Infinity:
- Tarboton, D.G. (1997):
    'A new method for the determination of flow directions and upslope areas in grid digital elevation models',
    Water Resources Research, Vol.33, No.2, p.309-319

Multiple Flow Direction:
- Freeman, G.T. (1991):
    'Calculating catchment area with divergent flow based on a regular grid',
    Computers and Geosciences, 17:413-22

- Quinn, P.F. / Beven, K.J. / Chevallier, P. / Planchon, O. (1991):
    'The prediction of hillslope flow paths for distributed hydrological modelling using digital terrain models',
    Hydrological Processes, 5:59-79

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This version uses all valid cells (not 'no data' values) of a given target grid to determine the contributing area. In case no target grid is provided as input, the specified x/y coordinates are used as target point.<hr><h4>Parameters</h4><table border="1" width="100%" valign="top" cellpadding="5" rules="all"><tr><th>Name</th><th>Type</th><th>Identifier</th><th>Description</th><th>Constraints</th></tr>
<tr><th colspan="5">Input</th></tr><tr><td>Target Area (*)</td><td>Grid (optional input)</td><td>TARGET</td><td></td><td></td></tr><tr><td>Elevation </td><td>Grid (input)</td><td>ELEVATION</td><td></td><td></td></tr><tr><td>Sink Routes (*)</td><td>Grid (optional input)</td><td>SINKROUTE</td><td></td><td></td></tr><tr><th colspan="5">Output</th></tr><tr><td>Upslope Area</td><td>Grid (output)</td><td>AREA</td><td></td><td></td></tr><tr><th colspan="5">Options</th></tr><tr><td>Target X coordinate</td><td>Floating point</td><td>TARGET_PT_X</td><td>The x-coordinate of the target point in world coordinates [map units]</td><td>Default: 0.000000</td></tr><tr><td>Target Y coordinate</td><td>Floating point</td><td>TARGET_PT_Y</td><td>The y-coordinate of the target point in world coordinates [map units]</td><td>Default: 0.000000</td></tr><tr><td>Method</td><td>Choice</td><td>METHOD</td><td></td><td>Available Choices:
[0] Deterministic 8
[1] Deterministic Infinity
[2] Multiple Flow Direction
Default: 2</td></tr><tr><td>Convergence</td><td>Floating point</td><td>CONVERGE</td><td>Convergence factor for Multiple Flow Direction algorithm</td><td>Minimum: 0.001000
Default: 1.100000</td></tr></table>(*) <i>optional</i>